But such wins do little to overcome his fundamental problem. Many conservatives just aren't buying what he's selling. And that alone gives his remaining rivals for the Republican presidential nomination reason enough to stay in the race.

Sarah Palin no doubt spoke for many conservatives with her response to a question from Chris Wallace on Fox News Sunday as to whether she trusted that Romney was an "instinctive conservative" or "convinced" by his assertion of loyalty to the political right's cause:

"I trust that his idea of conservatism is evolving. And I base this on a pretty moderate past that he has had and, in some cases, a liberal past...

"... I am not convinced and I don't think that the majority of GOP and independent voters are convinced. And that is why you don't see Romney get over the hump. He's still in the 30-percentile mark when it comes to approval and primary wins and caucus wins. He still hasn't risen above that yet because we are not convinced.

Palin isn't exactly objective, having urged voters in South Carolina and Florida to support Newt Gingrich, for instance.

Despite that, it's hard to deny the evidence appears to support her.

The tepidness Romney elicits from many Republicans as well as the juggernaut approach his campaign has taken against its rivals made it easy for the other GOP candidates to cast doubts even on Romney's weekend victories.

Romney won the CPAC straw vote with 38 percent to Santorum's 31 percent while Gingrich was at 15 percent and Rep. Ron Paul of Texas at 12 percent. Santorum sought to cast a cloud over the results by suggesting that perhaps the Romney campaign had skewed the results by buying CPAC tickets for its supporters.

In Maine, Romney won 39 percent of the vote with Paul winning 36 percent. But Paul's campaign manager complained that Maine GOP officials called the race for Romney even though one county postponed its voting for a week due to weather.

(Nate Silver of the FiveThirtyEight blog examines the Paul campaign's argument and concludes that while it's unlikely Paul would win if Washington County had held its vote as scheduled, with the extra time Paul might if his campaign can use the additional week to outdo Romney in getting supporters to caucus sites.)

In any event, the new week starts essentially where the old one ended. Santorum continues to lay claim to an important part of the Republican Party as Gingrich recedes and Romney struggles to recapture the aura of inevitability he and his campaign have counted on carrying them to the nomination.

After losing caucuses in Minnesota and Colorado and a primary in Missouri last week to Santorum, Romney still needs some decisive wins in states that come later in February and on Super Tuesday to lessen the talk of a primary contest going all the way to the Tampa convention.

But there could be trouble brewing for Romney in, of all places, Michigan, the state where his father, George, was once a popular governor and where Romney spent much of his childhood.

A new American Research Group poll done after last week's Republican contests puts Santorum up over Romney by six percentage points among likely voters, 33 percent to 27 percent.